trpl-zh-cn/listings/ch04-understanding-ownership/no-listing-11-muts-in-separate-scopes/src/main.rs

fn main() {
    // ANCHOR: here
    let mut s = String::from("hello");

    {
        let r1 = &mut s;
    } // r1 在这里离开了作用域，所以我们完全可以创建一个新的引用

    let r2 = &mut s;
    // ANCHOR_END: here
}